1. Field of the Invention
The present invention relates to a process for producing polybutene-1. More particularly, it relates to a process for producing polybutene-1 having high isotactic characteristic by using a novel catalyst system which has less deterioration of catalytic activity even at high polymerization temperature and has high catalytic activity which need not to be separated after a polymerization.
2. Description of the Prior Arts
Heretofore, various proposals have been found on catalysts for producing isotactic polyolefins having high isotactic characteristic from .alpha.-olefin such as butene-1. The well-known catalytic system comprises a solid titanium halide and an organoaluminum compound such as dialkylaluminum halide.
Thus, isotactic polymers having high isotactic characteristic can be obtained by using such known catalysts, however, such catalysts have not enough high catalytic activity so as to require a step of separating a catalyst residue remained in the resulting polymer. In order to overcome the problem, various methods have been proposed to improve remarkably a polymer productivity per a transition metal and a solid catalytic component by depositing a transition metal compound on a carrier and to eliminate substantially a step of separating the catalyst residue.
As one method, it has been proposed to use a catalyst comprising an organoaluminum compound and an organic acid ester and a solid catalytic component obtained by reacting a titanium halide, in the presence of an organic acid ester, with a reaction product of a halogen containing-aluminum and/or silicon compound with a reaction product of a specific silicon compound with Grignard reagent (Japanese Patent Application No. 112488/1978).
In the further studies, it has been found that the above-mentioned catalytic system has high catalytic activity for producing polyolefins having high isotactic characteristic at high yield. However, when the catalytic system is used for polymerization of butene-1, the catalytic activity of the catalytic system is deteriorated depending upon rising of the polymerization temperature. This tendency is remarkably higher at a polymerization temperature of 60.degree. C. or higher and the polymer productivity of the catalyst is remarkably deteriorated as the phenomenon.